Kopplung der phänologischen Entwicklung der Rosskastanie [Aesculus hippocastnum L.] mit Lebenszyklus und Verhalten der Kastanienminiermotte [Cameraria ohridella Deschka & Dimic] (Lepidoptera: Gracillariidae)

The horse chestnut leafminer Cameraria ohridella, described 1986 in Macedonia, had spread over Central Europe in the last few years causing conspicuous damage on chestnuts (Aesculus hippocastanum) in alleys, parks and forests. This paper shows the coupling of the life cycle and behaviour of this insect with the phenological growth of the chestnut. The enhanced BBCH-Scale (STAUSS et al., 1994) has been used to describe the phenological data of weekly examined chestnuts in Dresden (capital of Saxony) and in the region of Gottingen (Lower Saxony). In parallel the development of C. ohridella was examined by sampling leaves from the investigated trees; the appearance of adults was registered by counting imagines resting at chestnut stems. The first generation of C. ohridella shows a noticeable temporally coincidence with flowering of the chestnut and the end of leaf development. Examinations of different authors confirm this observation for different middle-european regions. Control strategy of C. ohridella depending on phenological estimation of the chestnut without an observation of the instars of this taxon is only applicable during the first half of the year. Forming hibernating pupae by every generation, partially different speed of development and an incomplete 3 r d generation complicate the assignment of phenological phases of the chestnut to instars of C. ohridella in the second half of the year. Behavioural assays yielded a sophisticated mechanism of host finding and selection. The chemical basis of olfactory preference of C. ohridella towards A. hippocastanum as affected by phenological states of the tree was analysed by gaschromatography-mass spectrometry coupled with electroantennographic detection GC-MS/EAD.